We were discussing this at work just this week as UPS is saying the same thing for package car drivers because of their vehicles size.
My point is, why should it matter? A driver required to work long hours by his employer can kill someone just as easily in a FedEx van, a UPS PC, or in my Feeder equipment.
And the "you're not really driving all that time because you're delivering to a stop" is BS too. It's not that you are driving that fatigues you, it's the long hours. What's the dangerous part is that when you DO become fatigued you'll be at the wheel eventually.
No one cares when the fatigued driver trips over a rake in a yard. But kill some kid on a bike and it'll have their attention.